Ephtal is a great sage who originally reincarnated into a fantasy world from modern Earth. Driven by a dream to master magic, he devoted his entire life to its study, only to confront the crushing reality of his own lack of talent. After falling into despair over his limits, he ultimately died of old age, his greatest ambition unfulfilled.

But his story does not end there. Four hundred years later, Ephtal is reincarnated a second time, awakening in a world that has changed drastically. He retains all the magical knowledge and abilities he painstakingly acquired in his previous life. However, he soon discovers that the civilization of magic has experienced a significant decline over the centuries; powerful spells that were once common have become rare legends. In this new era, the "talentless" sage who once failed to reach the peak of magic finds that his abilities are now utterly unparalleled and overpowered.

The story follows Ephtal as he enrolls in a prestigious magic academy, determined to finally achieve his goal. Here, he is joined by Anastasia, a slave girl who becomes a key companion, and encounters Marin, the headmaster of the academy who was once his disciple in his previous life. The central conflict arises from Ephtal's attempts to navigate this new world and its academy, using his ancient, superior magic to overcome challenges that stump contemporary mages. Notable narrative arcs include his initial reincarnation and discovery of the world's magical decline, his enrollment and rise within the academy where he overturns common sense with his extraordinary power, and the complex reunion with his former disciple, now an elderly headmaster who recognizes his true identity.